copper cylinder heads?

Nikolas Britton · Jul 21, 2008

How come they don't make cylinder heads out of copper? Copper is one of the most thermally conductive materials know to man and it's also stronger then aluminium.

Also, why don't engine designers take advantage of the peltier effect or even just plain old vapor compression refrigeration?

Leland · Jul 21, 2008

to soft to handle the pressures ,and it's to costly to start with as well

Anonymous-0 · Jul 21, 2008

Highly thermally conductive cylinder heads and pistons are actually undesireable from a thermodynamic efficiency point of view. You want to keep the heat of combustion inside the cylinder where it promotes the expansion of gasses and production of useful work, not dump the heat into the water jacket where it represents energy wasted.

For this reason, there have been a number of experiments with ceramic pistons and even ceramic engines. There are still too many problems with manufacturability and durability, but these materials will be used one day.

Aluminum is sometimes chosen over cast iron for cylinder heads because it is light and saves weight, something important in cars (but not in tractors). Copper doesn't save weight over cast iron, making another strike against that choice.

Peltier cooling and vapor-cycle refrigeration are not used because efficiently removing large amounts of heat from the cylinder head and block is not a desireable end goal. The cooling system of an engine is a necessary evil, and needs to work just well enough to keep the engine from melting down. Circulating water (coolant) does this just fine.

Mathias NY · Jul 21, 2008

Have you looked at the price of Copper? Performance asside, Copper is expensive. Even at scrap prices Copper is ~4.5 times more expensive than Aluminum. Whatever thermal conductive gains there might be, would not offset the higher material cost.

dlplost · Jul 21, 2008

$$$$ Priced copper lately?

big fred · Jul 21, 2008

Stronger than aluminum? Not even close.

RobMD · Jul 21, 2008

Copper heads? You sure you're not talking about snakes?

MarkB_MI · Jul 21, 2008

They don't make cylinder heads out of copper for the same reasons they don't make them out of gold: Too heavy, too soft and too expensive.

A friend of mine is an engine block engineer. He says that cast iron is as close as you're going to get to an ideal material for engine blocks and heads: Tough, inexpensive, easily milled, good thermal properties (including minimal expansion). But it's heavy, which is why pretty much all new automotive engine designs are aluminum. And aluminum is used in spite of its thermal properties rather than because of them.

Actually there are some alloys of copper (such as manganese bronze) that I'm sure you could make an engine from. But you never see it, even in marine applications; bronze is way too expensive and heavy for most applications.

copper cylinder heads?

Nikolas Britton

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Leland

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Anonymous-0

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Mathias NY

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dlplost

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big fred

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RobMD

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MarkB_MI

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